Composition material for sound transmitters



-0l:. 14, 1930. o, PLATTER ET AL 1,778,164

COMPOSITION MATERIAL FOR SOUND TRANSMITTERS Filed April 8/ 1927 gwueniot Umal RPZatzer Z'Jasper T561 Patented Oct. 14?, 1939 rates UFTE ORVAL R. PLATTER AND JASPER T. BALL, OF NORTH VERNON, INDIANA COMPOSTTION MATERIAL FOR SOUND TRANSMITTERS Application filed April 8, 1927. Serial No. 182,176.

In the manufacture of musical instruments it is important that material be employed for the sound transmitting or amplifying parts of such resonant qualities as will be most effective and desirable for the pur pose. Our invention relates to the material of which such parts may be manufactured whereby such. results are accomplished; and it consists of a composition of certain materials so combined and formed as to provide a product for such use embodying the desirable qualities for the purpose in a marked degree, all as will be hereinafter more fully described and claimed.

The composition as a whole comprises the combination of a number of substances formed into a pliable or plastic mass which may be molded or otherwise formed into any desired shape best adapted for constructing the form of device required for any particular use,such as sound amplifiers, phonograph horns, radio horns, etc.

Referring to the accompanying drawings, Which are made a part hereot and on which similar reference characters indicate similar parts,

Figure 1 is a fragmentary side elevation illustrating the method of carrying out our improved process,

Figure 2 a similar view illustrating another step in the process, 1

Figure 3 a section on the line 88 of Fig. 2,

Figure 4 a step following that shown in Fig. 2, with a portion cut out to permit the bending of the horn, and

Figure 5 shows a sectional part elevational view showing the elbow or bent portion completed.

Referring to the drawings The product may employ as a base a sheet of material 10 of a nature similar to that commonly employed as a floor covering, for example, so called rug border. Said base consists of a sheet of felted fibrous material impregnated with bituminous or resinous material, as a sheet of felted fibrous material impregnated with asphalt and coal tar, or coal tar pitches, painted on the back and having a varnish or celluloid finish on the front. Either rag or paper felt may be employed and red Venetian paint is usually employed for the bottom surface. This material being provided in sheet form, either from commercial supplies or special manufacture, is cut to a pattern as desired for the purpose as, for example, for a sound transmitter horn of any desired size. The sheet of material thus cut of appropriate pattern is formed around a cone-shaped hollow metal form or cylinder 11 into which steam is introduced and discharged through inlets and outlets 12 and 13 to heat the interior of the cylinder so that the sheet of material will be heated to reduce it to a pliable or even plastic condition, so that it may be shaped around the cylinder and stay in the shape in which it is thus formed. It is then taken off of the heated metal cylinder and placed on a wood form 14: in which a groove 15 is provided running the entire length of the form, in which groove 7 is mounted a wood strip 16 about threeeighths of an inch square. The edges of the tubular material are lapped over this wood strip and secured thereto and to each other by tacks or staples 17 driven through the material and into the wood strip. To the outside of this tube thus formed, two coats of heavy lrraft paper 18 and 19 are applied, the first covering being secured by an adhesive consisting of a mixture of eight parts dextrin so and two parts of plaster of Paris. Outside of this covering is then applied the second coat or sheet of paper pound or 100 pound kraft paper) by the use of the same or similar adhesive substance. The tube or horn is then 35 so cut or scored as shown at 20 that it can be bent to form it into the shape desired. The joints formed by these cuts or scores are then covered and fastened together with two applications of the heavy kraft paper 21 using as an adhesive a mixture of ten parts flour paste, one part ammonia and two parts plaster of Paris.

After the horn or sound transmitter is thus formed it is given a coat of shellac varnish 22' on the exterior and is then dipped in a composition of shellac anl black coloring matter 23. This dipping process is repeated in order to secure the desired thickness of covering and stability of the horn.

It will be understood, of course, that while we have described the process employed in the formation of a tubular sound transmitter as a loud speaker horn for phonographs and radio instruments, it may be used for other purposes or other sound transmitters for which it may be found suitable, the invention consisting in providing a material for the purpose explained composed essentially of felted fibrous material impregnated with bituminous or resinous material and having superimposed thereon a covering consisting of multiple layers of heavy paper secured thereto by an adhesive composed of plaster of Paris, flour paste and ammonia and finally coated upon its outside with shellac varnish and a compositionof shellac and black coloring matter and upon its inside covered with an appropriate coating of paint.

it Will be understood, of course, that various-modifications in the construction and in the process of manufacture may be employed without departing from our invention, and that the material may be formed either by using the sheets of material, already manufactured and obtainable in the market, or it may be manufactured and built up from the beginning by a continuous process. We do not desire, therefore, to limit our invention to the eXact'ingredients mentioned or tothe particular process described but only as may be required by the appended claims.

Having thus described our invention, what "We claim as new and desire to securevby Letters Patent is:

1. The method of manufacturing armate-ial to be used in making tone arms comprising forming felted sheet material about a heated metal form, removing it from said form and positioning it on a form having a groove therein in which groove is placed a wooden strip, lapping the edges over this strip, securing them thereto, covering the whole with layers of paper secured thereto by an adhesive and coating it with a binder and coloring, substantially as set forth.

2. The process of manufacturing tone arms comprising forming felted material aboutea heated metal form, removing it. from said formand placing it on a form having means for producing a longitudinal rib in the tone arm,applying a covering thereto by an adhesive, andcoating the whole, substantially as set forth.

3. The process of manufacturing tone 

